Convergent adaptations: bitter manioc cultivation systems in fertile anthropogenic dark earths and floodplain soils in central Amazonia

Shifting cultivation in the humid tropics is incredibly diverse, yet research tends to focus on one type: long-fallow shifting cultivation. While it is a typical adaptation to the highly-weathered nutrient-poor soils of the Amazonian terra firme, fertile environments in the region offer opportunities for agricultural intensification. We hypothesized that Amazonian people have developed divergent bitter manioc cultivation systems as adaptations to the properties of different soils. We compared bitter manioc cultivation in two nutrient-rich and two nutrient-poor soils, along the middle Madeira River in Central Amazonia. We interviewed 249 farmers in 6 localities, sampled their manioc fields, and carried out genetic analysis of bitter manioc landraces. While cultivation in the two richer soils at different localities was characterized by fast-maturing, low-starch manioc landraces, with shorter cropping periods and shorter fallows, the predominant manioc landraces in these soils were generally not genetically similar. Rather, predominant landraces in each of these two fertile soils have emerged from separate selective trajectories which produced landraces that converged for fast-maturing low-starch traits adapted to intensified swidden systems in fertile soils. This contrasts with the more extensive cultivation systems found in the two poorer soils at different localities, characterized by the prevalence of slow-maturing high-starch landraces, longer cropping periods and longer fallows, typical of previous studies. Farmers plant different assemblages of bitter manioc landraces in different soils and the most popular landraces were shown to exhibit significantly different yields when planted in different soils. Farmers have selected different sets of landraces with different perceived agronomic characteristics, along with different fallow lengths, as adaptations to the specific properties of each agroecological micro-environment. These findings open up new avenues for research and debate concerning the origins, evolution, history and contemporary cultivation of bitter manioc in Amazonia and beyond

Long-distance dispersal of the coconut palm by migration within the coral atoll ecosystem

Background The location of the original home of the coconut palm, Cocos nucifera, and the extent of its natural dispersal are not known. Proponents of a South American origin must explain why it is not indigenous there and why it shows greatest diversity in southern Asia. Conversely, proponents of an Asian origin must explain why there are no Asian Cocoseae and why the closest botanical relative to Cocos is in South America. Both hypotheses share the common problems of how, when, where and in what directions long-distance dispersal occurred. Hypothesis These difficulties are resolved by accepting that C. nucifera originated and dispersed by populating emerging islands of the coral atoll ecosystem, where establishment conditions impose high selection pressures for survival. When lifted by wave action onto virtually sterile, soilless coralline rocks just above sea level and exposed to the full impact of the sun, seednuts must germinate, root and establish vigorous populations. The cavity within the nut augments the buoyancy provided by the thick husk, which in turn protects the embryo and, by delaying germination, simultaneously extends viability while floating and provides a moisture-retentive rooting medium for the young seedling. These adaptations allow coconuts to disperse widely through the coral atoll ecosystem. Conclusions The monthly production of fruit and the long floating duration ensure that viable seednuts are always available in the lagoon to replace those destroyed by hurricanes and tsunamis, or to populate newly emerged coral atolls elsewhere. Long-distance dispersal is secondary, because it was the spontaneous, independent migration of coral polyps on a prolonged geological time scale that generated new coral atolls in new areas where the coconuts would be amongst the earliest inhabitants. The coconut palm became an intermittent, itinerant, pioneer endemic there, and also on suitable beaches on volcanic or large islands and continental coastlines. © 2013 The Author. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved

Práticas agrícolas de conseqüências genéticas que possibilitaram aos índios da Amazônia uma melhor adaptação às condições ecológicas da região

Cultivars of food plants actually found in Amazonia that are different from present days wild varieties have been selected by the indians in the last 10,000 years in South America and likely in the last 4,000 to 1,000 years by Amazonian tribes. This paper analyses 40 cultivars of manhioc of Desana and 13 of Tikuna. Surveys in 7 indian tribes reveal an average of 22 cultivars per tribe. Discussed are wild and selected (by the indians) "varieties" of several fruit trees: abiu Pouteria caimito), sapota (Matisia cordata), sapoti (Manilkara zapota), pupunha (Bactris gasipaes), pineapple (Ananas exculenta). Attention is given to some domesticated tuber plants (yam, sweet-potatoes, taro. leren) and to cupá (Cissus gongilodes); this last one, due to the small distribution may be one of the most recent domestications. It is suggested that the duck (Cairina moschata) domesticated itself in order to occupy the empty niche near the tribes.Os cultivares de plantas, de valor alimentício, encontrados na Amazônia, diferentes da população selvagem encontrada nas matas, foram selecionados pelos índios nos últimos 10.000 anos, para a América do Sul inteira e, possivelmente, nos últimos 4000 a 1000 anos para as plantas domesticadas na Amazônia. Este trabalho analisa 40 cultivares de mandiocas e macaxeiras dos Desâna e 13 dos Tikúna. Contagens em 7 tribos revelaram uma média de 22 cultivares por tribo. Indica-se para as fruteirasabiu, sapota, sapoti, pupunha, abacaxi, o tamanho e características das plantas selvagens e das selecionadas pelos índios. Mencionam-se, também, algumas tuberosas (cará, batata-doce, taioba, ariá, caroço-de-umari) domesticadas e o cupá (Cissus gongilodes); este último talvez seja uma das domesticações mais recentes. Sugere-se que o pato (Cairina moschata) se tenha autodomesticado, por meio de poucas mutações, com o que ocuparia um nicho ecológico vazio

Observações sobre autocompatibilidade em pupunha (Bactris gasipaes H.B.K., Palmae)

The pejibaye appears to have two strategies to insure cross-pollination. One of these appears to be a quantitative genetic factor inhibiting self -pollination. To study this factor two series of controlled self-pollinations were made in two different juvenile populations. The first population presented an average of 19,121 self-compatibility, measured as percentage of fertil fruit produced from all. flowers. However the coefficient of variation was extremely high. Open-pollination on the same trees produced only 22% fertil fruit, with a lower coefficient, of variation, suggesting that fruit, set was generally pooh. in this population at that time. The second population presented an average of 37.621 self-compatibility, with a lower coefficient of variation. Variation within trees was also detected and shown to be considerable. Overall, self-compatibility varied from 0 to 81%, with an non-normal distribution. The use of juvenile plants may be the reason for high variability within trees. Although little self-incompatibility was found in these populations, this characteristic is recomended as a descriptor for germplasm banks and should be obtained on adult plants to avoid high juvenile variability.A pupunha aparentemente, possui duas estratégias que asseguram a sua polinização cruzada. Uma delas parece ser um fator genético quantitativo que inibe a auto-polinização. Para estudar este fator, duas series de polinização controlada foram feitas em duas diferentes populações juvenis. A primeira população apresentou uma media, de 19,2% de auto-compatibilidade, medida em percentagem de frutos férteis produzidos em relação a todas as flores. Entretanto, o coeficiente de variação foi extremamente alto. A polinização aberta em algumas plantas produziu 22% de frutos férteis, com um coeficiente de variação menor, sugerindo que, o " fruit set" foi, em geral, baixo nutria população, naquela vez. A segunda população, apresentou em media 37,62% de auto-compatibilidade, com um coeficiente de variação menor. Variação entre as árvores foi também detectada e mostrou ser considerável. Além do mais, a auto-compatibilidade variou de 0 a 81%, em distribuição normal. 0 uso de plantas juvenis pode ser a razão da alta variabilidade entre plantas. Apesar da pouca auto-compatibilidade encontrada nestas populações, esta característica é recomendada como descritor para bancos de germoplasma e deve ser obtida em plantas adultas para evitar a alta variabilidade juvenil

Phenology and yield of Abiu (Pouteria caimito) in Central Amazonia

The abiu (Pouteria caimito (Ruiz et Pavon) Radlk., Sapotaceac) is a popular native Amazonian fruit and is attracting commercial attention in other tropical regions. Phenological and yield information is useful to growers and vendors for planning plantation management and commercialization. In Central Amazonia the abiu presented three periods of intense flowering each year from 1980 to 1982 (two during the rainy season, one during the dry season), followed a month later by fruiting, with considerable variation from tree to tree so that some fruit were available during at least seven months (April to October). The abiu flowered abundantly in each period, but only 1.4 to 3.0% of the flowers set fruit, and this percentage appeared to be affected by plant nutritional status and phytosanitary stress. On the nutrient poor Oxisols in Central Amazonia abiu fruit varied in weight from 57 to 238 g (mean ± s.d. = 120 ± 46 g), with 42% edible pulp. Anual fruit yield was estimated at 77 ± 28 kg/tree, equivalent to 21 t/ha at 6 x 6 m spacing. Insect visitors included apparent pollinators and pests (notably Anastrepha serpentina), and phytosanitary problems increased during the period of observation.O abiu (Pouteria caimito (Ruiz et Pavon) Radlk., Sapotaceae) é uma das fruteiras nativas da Amazônia mais populares entre os consumidores locais e vem atraindo a atenção do mercado em outras regiões tropicais. Informações sobre fenologia e produtividade são úteis tanto para o produtor com para o comerciante para planejar o manejo da plantação c a comercialização dos frutos. Na Amazônia central, o abiu apresentou três períodos de floração intensa por ano entre 1980 e 1982 (duas durante a estação chuvosa, uma durante a estação seca), seguida no próximo mês pela frutificação, com variação considerável de planta para planta, de forma que alguns frutos estavam disponíveis durante pelo menos sete meses (abril a outubro). O abieiro floresceu abundantamente em cada período, mas somente 1,4 a 3,0% das flores vingaram, e esta porcentagem aparentamente foi afetada pelo estado nutricional das plantas e por problemas fitossanitários. Nos Latossolos pobres em nutrientes da Amazônia central, o peso dos frutos de abiu variou de 57 a 238 g (media ± d.p. = 120 ± 46 g), com 42% de polpa comestível. A produtividade anual foi estimada em 77 ± 28 kg/planta, equivalente a 21 t/ha no espaçamento de 6 x 6 m. Os insetos visitantes incluíram possíveis polinizadores e pragas, como a mosca da fruta (Anastrepha serpentina). Problemas fitossanitários aumentaram ao longo do período de observações